kreta/Kreta.WebApi/User/Kreta.User.WebApi/Attributes/ApiKeyAuthorizationAttribute.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;
using Kreta.User.WebApi.Infrastructure;

namespace Kreta.User.WebApi.Attributes
{
    internal class ApiKeyAuthorizationAttribute : AuthorizationFilterAttribute, IOverrideFilter
    {
        const string ApiKey = nameof(ApiKey);

        public Type FiltersToOverride
        {
            get
            {
                return typeof(IAuthorizationFilter);
            }
        }

        private bool AccessGratnedByApiKey(KeyValuePair<string, IEnumerable<string>> apiKeyHeader)
        {
            if (apiKeyHeader.Value != null)
            {
                string targetApiKey = apiKeyHeader.Value?.SingleOrDefault();

                if (!string.IsNullOrWhiteSpace(targetApiKey) && targetApiKey == ApiKeyConfiguration.Instance.ApiKey)
                {
                    return true;
                }
            }

            return false;
        }

        public override void OnAuthorization(HttpActionContext actionContext)
        {
            var headers = actionContext.Request.Headers;

            var apiKeyHeader = headers.SingleOrDefault(x => x.Key.Equals(ApiKey, StringComparison.InvariantCultureIgnoreCase));

            if (!AccessGratnedByApiKey(apiKeyHeader))
            {
                actionContext.Response = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.Unauthorized);
            }
        }
    }
}